Devil Dust iron/sew on patch.  This is part of the apothicary label collection. Full collection can be purchased at a discount.
 
We use polyester threads on a 65% polyester /35% cotton twill. Each patch is hand cut with a heated knife to melt the edges leaving a nice clean finish. The iron on backing helps lock in stitches so nothing can unravel.  You can either iron on the patch to your garment/item or you can sew the patch on without gumming up your needle.